Files and streams In Java

Sardar VallabhBhai Patel Institute
of Technology
 Name- RAJAN
SHAH
 Topic: Files In
JAVA

I/O Stream
 Input Stream: It is a stream which may be
connected with different i/p devices like
keyboard, file or network socket. It is used to
generate data.
 Output Stream: It is used to produce data and
may be connected with different output devices
like monitor, file, network socket.

Files and Streams
 File processing with classes in package java.io
 FileInputStream for
byte-by-byte input from a file
 FileOutputStream for
byte-by-byte output to a file
 FileReader for char-by-char
input from a file
 FileWriter for char-by-char
output to a file

Difference
byte Stream char Stream
1. It deals with byte.
2. Used to manipulate
data in binary
format.
3. Mainly uses audio,
video, img, txt files.
4. InputStream and
OutputStream are
top two abstract
classes of byte
Stream.
1. It deals with char or
Strings.
2. Used to manipulate
data in Unicode.
3. Can be used only
with txt files.
4. Reader & Writer are
top two abstract
classes of char
Stream.

Constructors, Methods Of
FileInputStream
 CONSTRUCTORS:
 FileInputStream(String fname);
 FileInputStream(File F);
 FileInputStream(String fold, String fname);
 METHODS:
 int read(); // n= fis.read(); // n is the byte read.

Constructors, Methods Of
FileOutputStream
 CONSTRUCTORS:
 FileOutputStream(String fname);
 FileOutputStream(File F);
 FileOutputStream(String fname, boolean app);
 METHODS:
 void write(int n); //write(n); //n is the byte to be
written
 void write(byte []b); // writes the array contents to
file.

Example: FileInputStream
 import java.io.*;
public class ReadStringFromFile {
public static void main(String[] args)
{
File file = new File("C://FileIO//ReadString.txt");
int ch;
StringBuffer strContent = new StringBuffer("");
FileInputStream fin = null;
try
{
fin = new FileInputStream(file);

Continue...
while( (ch = fin.read()) != -1)
strContent.append((char)ch);
fin.close();
}
catch(Exception e){
System.out.println(e);
}
System.out.println("File contents :");
System.out.println(strContent);
}
}

Example: FileOutputStream
 import java.io.FileInputStream;
 import java.io.FileOutputStream;
 import java.io.IOException;
public class FileOutputStreamDemo {
public static void main(String[] args) throws IOException
{
byte[] b = {65,66,67,68,69};
int i=0;
char c;
try{
FileOutputStream fos=new
FileOutputStream("C://test.txt");
fos.write(b);

Continue...
fos.flush();
FileInputStream fis = new FileInputStream("C://test.txt");
while((i=fis.read())!=-1) {
c=(char)i;
System.out.print(c); }
}catch(Exception ex) {ex.printStackTrace(); }
finally{
if(fos!=null)
fos.close();
if(fis!=null)
fis.close(); }
} }

Constructors, Methods Of FileReader
 CONSTRUCTORS:
 FileReader(String fname);
 FileReader(File F);
 FileReader(String fold, String fname);
 METHODS:
 int read(); // n= fis.read(); // n is the char read.
 int read(char [] c, int offset, int len); // reads
character into an array and returns the number of
chars read.

Constructors, Methods Of FileWriter
 CONSTRUCTORS:
 FileWriter(String fname);
 FileWriter(File F);
 FileWriter(String fold, String fname);
 METHODS:
 void write(String n); // write(n); //n is the String to be
written to file.
 public void write(char [] c, int offset, int len); // Writes a
portion of an array of characters starting from offset
and with a length of len.
 public void write(String s, int offset, int len);

Example: FileReader
public class FileRead {
public static void main(String args[]) throws
IOException {
File file = new File("Hello1.txt");
file.createNewFile(); //returns true if file is created
FileWriter fw = new FileWriter(file);
fw.write("Thisn isn ann examplen");
fw.flush();
fw.close();

Continue...
FileReader fr = new FileReader(file);
char [] a = new char[50];
fr.read(a); //reads content to array
for(char c : a)
System.out.print(c);
fr.close(); }
}

Example: FileReader using
BufferedReader
public class Reader {
public static void main(String[]args) throws
IOException{
FileReader fr = new FileReader("C:/test.txt");
BufferedReader br = new BufferedReader(in);
while (br.readLine() != null)
{ System.out.println(br.readLine()); }
fr.close();
}

Example: FileWriter
• import java.io.*;
class Simple{
public static void main(String args[]){
try{
FileWriter fw=new FileWriter("abc.txt");
fw.write(“Hello World");
fw.close();
}
catch(Exception e) {System.out.println(e);}
System.out.println(“Success");
}
}

 import java.io.BufferedWriter;
 import java.io.File;
 import java.io.FileWriter;
 import java.io.IOException;
public class BufferedWriterDemo {
public static void main(String[] args) throws IOException
{
File f = new File("java2learn.txt");
System.out.println(f.exists());
BufferedWriter bw = new BufferedWriter(new
FileWriter(f));
char[] ch1 = { 'a', 'b', 'c', 'd' };
bw.write(ch1);
} }

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